The present invention relates to multilayer packaging films comprising modified polyamide.
A film layer comprising polyamide may be useful in providing enhanced oxygen barrier attributes to a packaging film. One such polyamide is an amorphous polyamide such as nylon-6,I/6,T. This polyamide normally has equal amounts of the free amino end group (i.e., the —NH2 end group) and the free carboxyl end group (i.e., the —COOH end group). However, these end groups in some environments may react to form salts or react with other polymer functional groups. For example, one or both of the free end groups of the polyamide may tend to react with the contents of a package incorporating the polyamide.
It may therefore be useful to provide the polyamide with one or more of the free end groups of the polyamide chain being modified or “capped” to a desired degree. For example, the free amino end group and/or the free carboxyl end group of the polyamide chain may be preferentially modified or “capped” to reduce the reactivity of the polyamide. The modified polyamide may provide a reduced reactivity with the packaged contents.
However, a film layer comprising such a modified polyamide may have an unacceptably lowered adhesion strength to an adjacent film layer. For example, it is known to provide a film having a modified amorphous nylon-6,I/6,T layer adjacent to an anhydride-modified polyolefin tie layer; however, such a film has unacceptably low bond strength between these layers.